Price-to-Earnings Ratio Calculator

Created by Arunangshu DasReviewed Nov 9, 2026

Calculate trailing or forward P/E using matching share price and earnings per share.

Use price and EPS for the same security, share basis and currency units.

Trailing P/E

Enter the price and EPS or load the worked example.

P/E is a dimensionless multiple. A forward result depends on the earnings estimate you supply.

Understand the earnings denominator

Compare trailing and forward figures and see what zero or negative earnings mean.

Read the complete Price-to-Earnings Ratio guide

Formula and methodology

P/E = share price ÷ earnings per share, when EPS is positive.

Divide a positive share price by positive earnings per share. Use the same currency units and share basis for both. The result is dimensionless and expressed as a multiple.

Definitions

P/E measures the share price per unit of positive earnings per share. Trailing EPS covers the last 12 months of actual earnings. Forward EPS is an estimate for the next 12 months.

Verified worked examples

A share price of 50 and trailing EPS of 2 give 25.00×. At the same price, forward EPS estimated at 4 gives 12.50×. The lower forward multiple comes from the larger estimated denominator.

Interpretation

Zero EPS makes the division undefined. Negative EPS indicates a loss and does not give a meaningful conventional P/E multiple. Very small positive EPS can produce a very large multiple.

Inputs and interpretation

Choose the EPS horizon. Enter positive price and signed EPS in matching units. Switching horizon clears EPS so that an actual figure cannot silently become a forecast.

Assumptions and limitations

Match the security, currency unit and share basis. When comparing multiples, use comparable horizons and check whether EPS is basic or diluted and reported or adjusted.

Supported domain and common mistakes

Each input accepts up to 48 trimmed characters and 12 decimal places, with magnitude no greater than 10^15. Positive multiples from 10^−27 through 10^27 are supported. Display rounds half-even to two decimals and marks positive values that round to zero.

Do not mix pounds with pence, share price with total earnings, or a depositary receipt with unmatched EPS for an underlying share. Avoid substituting a quarter's EPS or silently annualising it.

Frequently asked questions

How do I calculate P/E?

Divide positive share price by positive EPS on the same security and currency basis.

What is the difference between trailing and forward P/E?

Trailing uses actual EPS for the last 12 months. Forward uses a supplied estimate for the next 12 months.

What happens if EPS is zero?

Division by zero is undefined. The calculator explains this instead of displaying a multiple.

What if EPS is negative?

A loss does not give a meaningful conventional P/E. The calculator reports the loss state separately.

Can I use a share price in pence and EPS in pounds?

Convert the figures to matching units before entry. For example, 500 pence is 5 pounds.

Does a low P/E mean a stock is undervalued?

A low multiple can reflect different expectations, risks or earnings quality. This calculation does not estimate intrinsic value.

Sources and educational scope

Educational valuation multiple based on supplied inputs. No automatic forecasts, currency conversion, corporate-action adjustments, target prices or personalized investment advice.

Reviewed 2026-11-09. AI-assisted content under operator editorial responsibility. No independent expert financial review is claimed.